In the Witcher setting, a lot of scientific and medical knowledge went awol during the revolt on Thanedd island prior to the war with Nilfgaard, when the majority of sorcerers & sorceresses in the North were killed.
There's a codex entry in TW1 about the most talented healers being mages who develop vaccines and such, but at the time of the game there doesn't seem to be any left. Catriona's plague in Vizima for instance, has no vaccine nor is anyone even researching it.
At the time of the Witcher, there's basically only the Lodge of Sorceresses (about 10-15 female mages), some male court mages and a couple of rogue sorcerers left. And most of these seem to be more worried about political intrigue and advancing their own power rather than scientific research.
The situation in Nilfgaard might be wholly different. I'm guessing this area is much more advanced and civilized, but also keeping a tight rein on mages.